Synthesis of various quinolone compounds have been reported in the literature, e.g., U.S. Pat. No. 6,329,391; U.S. Pat. No. 6,803,469; B. Ledoussal et al., “Non 6-Fluoro Substituted Quinolone Antibacterials Structure and Activity”, J. Med Chem., Vol. 35, p. 198-200 (1992); V. Cecchetti et al., “Studies on 6-Aminoquinolines: Synthesis and Antibacterial Evaluation of 6-Amino-8-methylquinolones”, J. Med. Chem., Vol. 39, pp. 436-445 (1996); V. Cecchetti et al., “Potent 6-Desfluoro-8-methylquinolones as New Lead Compounds in Antibacterial Chemotherapy”, J. Med. Chem., Vol. 39, pp. 4952-4957 (1996)).
The antimicrobial quinolone compounds (3S,5S)-7-[3-amino-5-methyl-piperidinyl]-1-cyclopropyl-1,4-dihydro-8-methoxy-4-oxo-3-quinolinecarboxylic acid, and (3S,5R)-7-[3-amino-5-methyl-piperidinyl]-1-cyclopropyl-1,4-dihydro-8-methoxy-4-oxo-3-quinolinecarboxylic acid are disclosed in the U.S. Pat. No. 6,329,391, which is herein incorporated by reference in its entirety. However, there is a need in the art for improved methods for preparing these and like antimicrobial compounds.